An ethernet adapter provides your computer with a network port, generally used to connect to a router, modem or other computer through the use of a network cable. The large majority of computers and laptops come with an ethernet port pre-installed on their motherboards, however if these break or you are using a system that does not come with one pre-installed then you can by an adapter.

Ethernet adapters come with different interfaces for your system - usually PCI, PCI Express or USB - as well as different speeds from up to 10MB/s (10/100Mbps), 100MB/s (10/100/1000Mbps, also known as "Gigabit") to 1GB/s (10000Mbps or "10Gb").